Production of high octane gasoline by hydrocracking catalytic cracking products

Abstract

A moderate pressure hydrocracking process in which a highly aromatic, substantially dealkylated feedstock is processed directly to high octane gasoline by hydrocracking over a catalyst, preferably comprising a large pore size, crystalline alumino-silicate zeolite hydrocracking catalyst such as zeolite Y together with a hydrogenation-dehydrogenation component. The feedstock which is preferably a light cycle oil has an aromatic content of at least 50, usually at least 60 percent and an API gravity not more than 25. The hydrocracking typically operates at 600-1000 psig at moderate to high conversion leavels to maximize the production of monocyclic aromatics which provide the requisite octane value to the product gasoline. The unconverted products from the hydrocracker are recyclied to the catalytic cracking unit to obtain further improvements in gasoline yield and octane.

We claim: 
     
       1. A process for producing a high octane gasoline having an octane number of at least 87 (RON +0), which comprises hydrocracking a highly aromatic, substantially dealkylated hydrocarbon feed produced by the catalytic cracking of a hydrocarbon fraction, the feed having an initial boiling point of at least 300° F., an aromatic content of at least 50 weight percent, and a hydrogen content not more than 12.5 weight percent at a hydrogen partial pressure of not more than 1000 psig and a conversion to a hydrocarbon fraction which has a boiling range which extends from the boiling point of a C 5  hydrocarbon to 385° F., of not more than 50 vol. percent and numerically equal to not more than 0.05 times the hydrogen pressure (psig) to gasoline boiling range products, and recycling the fraction which is not converted during the hydrocracking to the catalytic cracking step. 
     
     
       2. A process according to claim 1 in which the recycled fraction comprises the fraction boiling above 385° F. 
     
     
       3. A process according to claim 1 in which the feed comprises a catalytic cracking cycle oil. 
     
     
       4. A process according to claim 1 in which the feed has a hydrogen content of 8.5 to 12.5 weight percent. 
     
     
       5. A process according to claim 1 in which the feed has an API gravity not more than 25. 
     
     
       6. A process according to claim 1 in which the feed has an API gravity not more than 20. 
     
     
       7. A process according to claim 1 in which the feed has an API gravity of 5 to 25. 
     
     
       8. A process according to claim 1 in which the hydrogen partial pressure during the hydrocracking is from 600 to 1000 psig. 
     
     
       9. A process according to claim 1 in which the hydrocracking is conducted in the presence of a large pore size hydrocracking catalyst having acidic and hydrogenation-dehydrogenation functionality. 
     
     
       10. A process according to claim 9 in which the hydrocracking catalyst comprises a large pore size crystalline alumino silicate zeolite. 
     
     
       11. A process according to claim 10 in which the zeolite comprises a zeolite having the structure of zeolite Y. 
     
     
       12. A process according to claim 10 in which the zeolite comprises zeolite Y, zeolite USY, zeolite De-AlY or zeolite UHP-Y. 
     
     
       13. A process according to claim 12 in which the zeolite has an alpha value up to 100. 
     
     
       14. A process according to claim 9 in which the hydrogenation-dehydrogenation functionality is provided by a metal component comprising at least one of nickel, tungsten, vanadium, molybdenum, cobalt and chromium. 
     
     
       15. A process according to claim 9 in which the hydrogenation-dehydrogenation functionality is provided by a metal component comprising at least one of platinum and palladium. 
     
     
       16. A process according to claim 1 in which the feed comprises a catalytic cracking cycle oil having an end point not more than 650° F. 
     
     
       17. A method according to claim 1 in which the feed is hydrotreated before being hydrocracked. 
     
     
       18. A method for the production of a high octane, hydrocracked gasoline, which comprises hydrocracking a highly aromatic, catalytically cracked light cut light cycle oil of the following properties: API°: not more than 25   Hydrogen content: 8.5-12.5 wt. pct.   Aromatic content: at least 60 wt. pct. under the following conditions:     Temperature: 700°-850° F.   H 2  partial pressure: 600-1000 psig   conversion to a hydrocarbon fraction which has a boiling range which extends from the boiling point of a C 5  hydrocarbon to 385° F., to gasoline boiling range products: not more than 50 vol. percent and numerically equal to not more than 0.05 times the hydrogen pressure (psig) in the presence of a hydrocracking catalyst comprising an aromatic-selective, large pore size crystalline, aluminosilicate zeolite having acidic functionality, a Constraint Index less than 2 and with an alpha value up to 100, and a metal component providing hydrogenation-dehydrogenation functionality, to form a hydrocracked gasoline boiling range product having an octane number of at least 87 (RON+0), and recycling the unconverted fraction to a catalytic cracking operation.     
     
     
       19. A process according to claim 18 in which the zeolite is zeolite Y, zeolite USY, zeolite UHP-Y or de-AlY. 
     
     
       20. A process according to claim 18 in which the metal component of the hydrocracking catalyst comprises at least one of nickel, tungsten, molybdenum, cobalt and vanadium. 
     
     
       21. A process according to claim 18 in which the conversion to gasoline boiling range products is 10 to 50 volume percent.